1. Technical Field
The present invention relates to a cord outlet structure of an electric instrument cabinet and, more specifically, the invention relates to a cord outlet structure of an electric instrument cabinet which, when the electric instrument cabinet includes not only an opening window serving as a cord outlet used to draw out power cords bound in a bundle from the inside of the cabinet to the outside thereof in the assembling process of the electric instrument or the like but also a cover molded integrally with the cabinet for closing the opening window after the cords are drawn out, can avoid generation of a clearance through which a foreign body can enter between the cover and the edge portions of the opening window when the opening window is closed by the cover.
2. Related Art
Conventionally, in the lower wall of a cabinet of an electric instrument, there is formed a relatively large opening window serving as a cord outlet used to draw out electric cords bound in a bundle from the inside of the cabinet to the outside thereof, and integrally with the cabinet, there is molded a cover; and, after the electric cords in a bundle are drawn out from the opening window in the assembling process of the electric instrument, the opening window is closed by the cover (for example, see Japanese Utility Model Registration No 3094353 and JP-UM-A-59-87178).
Here, FIG. 5 is a schematic perspective view of a cord outlet structure of an electric instrument cabinet according to another prior art, and FIG. 6 is a back view of the cord outlet structure, showing a state thereof when molds are removed after the cord outlet structure is molded. In this example, between the back wall 12 and lower wall 13 of a cabinet 1 (which is composed of a resin molding) of an electric instrument, there is formed an opening window 14 serving as a cord outlet; and, a cover 2 is formed integrally with the cabinet 1 through a resin hinge (not shown) composed of a thin part formed on the lower wall 13 side of the cabinet 1. The opening window 14 and cover 2 both have a substantially square-shaped contour shape with a rectangular shape as its base shape. Therefore, the left and right side edges 14a and 14b of the opening window 14 as well as the left and right side edges 2a and 2b are formed parallel to each other. Also, in the back wall 12 of the cabinet 1, there is formed a cord mounting part 15 on one side of the opening window 14 in such a manner that the cord mounting part 15 is continuous with the opening window 14, whereby a bushing 110, which is provided on the power cord 100 side and is fitted with and held by the cord mounting part 15, can be held by the cover 2 closed to the opening window 14 in such a manner that the bushing 110 can be prevented against removal from the cord mounting part 15. Also, the cover 2 closed to the opening window 14 can be fastened and connected by a mounting screw 16 to a boss portion 17 formed in the edge upper portion of the opening window 14.
On the other hand, in this type of electric instrument cabinet, when the cover 2 is closed to the opening window 14 and the opening window 14 is shut up, it is desired that a foreign body such as a coin made of an electric conductor or a metal wire member is prevented from being inserted into between the left and right edges 14a, 14b of the opening window 14 and cover 2. And, the UL regulations also require that measures should be taken to prevent the insertion of a coin into between the left and right edges 14a, 14b of the opening window 14 and cover 2.
In order to cope with this requirement, it is expected effective to take the following measures: that is, when the cabinet 1 is molded of resin, by enhancing the dimension precision of the opening width of the opening window 14 and the width of the cover 2, there can be prevented generation of a clearance between the left and right edges 14a, 14b of the opening window 14 and cover 2. However, to mold the cabinet 1 with such dimension precision requires an extremely high level of molding technique. In other words, even if such a dimension as to be able to prevent generation of a clearance is set in a mold design, generation of molding errors in the opening width of the opening window 14 and in the width of the cover 2 cannot be avoided due to the characteristics of resin used as the molding material and the level of the molding technique. As a result of this, the width of the cover 2 is inevitably too long to close the cover 2 to the opening window 14 properly.
In view of this, conventionally, in order to prevent such inconvenience that the width of the cover 2 is too long to close the cover 2 properly, the cover 2 is molded using a mold formed of a thin plate member such that the width of the cover 2 is slightly shorter than the opening width of the opening window 14. And, as measures for preventing a coin from being inserted through a clearance S which is generated as a result of the above short-width molding of the cover 2, as shown in FIG. 6, in two or more portions of the left and right edges 14a, 14b of the opening window 14 at given intervals (shorter intervals than the diameter of the coin), there are provided rib-shaped inward-facing projections 18a, 18b. Such provision of the projections 18a, 18b not only can prevent the insertion of the coin through the clearance S but also can prevent the occurrence of a situation that, when the cover 2 is closed to the opening window 14, the cover 2 can touch the edges 14a, 14b of the opening window 14 and cannot be thereby closed.